The subject of the present invention is a delustering composition for acetyl cellulose fibers. The subject of the present invention is furthermore a method for the production of the delustering composition and a method for delustering acetyl cellulose fibers and also the use of the delustered acetyl cellulose fibers in the production of cigarette filters and textile products.
The delustering of acetyl cellulose fibers may be effected using various methods. Two possible ways of delustering acetyl cellulose fibers are known from Kronos Leitfaden, Grundlagen and Anwendung von Kronos Titandioxid, published by Kronos Titanfabriken, 1967. One possible method consists in producing acetate chips having a relatively high content of TiO.sub.2 pigment (30 to 50% by weight TiO.sub.2 pigment). To this end, the TiO.sub.2 pigment is thoroughly dispersed in the acetyl cellulose in a heatable rolling mill. First of all, some diacetone alcohol and water is added to the mixture, in order to obtain a plastic substance. During the mixing process, the alcohol and the water evaporate, so that finally a strip of acetyl cellulose is produced in which the TiO.sub.2 pigment is regularly distributed. The chips produced therefrom can either be mixed with non-pigmented acetyl cellulose and then dissolved in acetone, but they may also be introduced directly into a spinning solution. Finally, there is the possibility of producing from these chips a solution of acetyl cellulose in acetone with a high TiO.sub.2 pigment content and not injecting this concentrate into the main stream of the spinning solution until shortly before the spinnerets. With this method, the shear force can be only poorly regulated.
The second possibility consists in producing a concentrate of TiO.sub.2 pigment in dilute acetyl cellulose solution with the aid of a suitable grinding apparatus, e.g. a ball mill. The solution contains approximately 7% by weight acetyl cellulose and approximately 25% by weight TiO.sub.2 pigment. After the dispersing operation, coarse contents of the pigment suspension are filtered off. Approximately 25% cellulose in acetone is introduced into an acetyl cellulose spinning solution and is mixed thoroughly therewith. This possible method of delustering acetyl cellulose fibers has the disadvantage that TiO.sub.2 tends to flocculate and be deposited in the acetate solutions, which causes further disadvantages.